This invention relates to absorbent articles such as diapers, incontinent articles, sanitary napkins, and the like. More particularly, this invention relates to absorbent articles having a topsheet and a film acquisition distribution layer (ADL) having a void volume space.
A variety of absorbent articles that are adapted to absorb body fluids are well known. Examples of absorbent articles include diapers, incontinent articles, and sanitary napkins.
One problem associated with known absorbent articles is waste product leakage, which may contaminate clothing articles, such as pants, shirts, and bedding. The amount of leakage experienced by a wearer can be reduced by increasing the rate that liquid enters the absorbent core. Therefore, an absorbent article wherein liquid rapidly penetrates the topsheet and is contained in the absorbent core will experience less leakage than an absorbent article wherein liquid is able to run across the topsheet before penetrating into the absorbent core. Consequently, run-off reduction reduces the amount of leakage associated with an absorbent article.
Another problem associated with absorbent articles is dryness of the skin contacting surface of the article. Generally, the drier the skin contacting surface, the more comfortable the absorbent article. Attempts have been made to reduce surface wetness in disposable diaper structures. For example, U.S. Pat. No. 3,945,386 issued to Anczurowski on Mar.23, 1976 and U.S. Pat. Nos. 3,965,906 and 3,994,299 issued to Karami on Jun. 29, 1976 and Nov. 30, 1976, respectively, teach diaper structures having a perforated thermoplastic film interposed between the topsheet and the absorbent core. U.S. Pat. No. 4,324,247 issued to Aziz on Apr. 13, 1982 describes an effort directed to both reducing run-off and reducing the surface wetness of absorbent articles.
In addition to the dryness of the skin contacting surface, the feel of the skin contacting surface is also an important consideration. One problem is that some consumers do not like the plastic feel associated with formed films. A number of efforts have been directed at improving the feel of the surface of absorbent articles. One example is described in U.S. Pat. No. 3,967,623 issued to Butterworth, et al. The Butterworth patent teaches an absorbent pad having a facing sheet made of a perforated thermoplastic web that has an integral fibrous or sueded outer surface.
An additional problem with typical absorbent articles, in particular adult incontinence diapers. As a wearer urinates a second time or more, a sensation of wetness is felt as unabsorbed fluid flows laterally through the topsheet from an area of saturated core material to an area of unsaturated core material for absorption. This sensation is highly uncomfortable and undesirable.
The products described in most of the above references, however, are less than ideal in achieving a good combination of all three desired properties of reduced surface run-off, improved ability to prevent a feeling of wetness of the topsheet, and improved feel.
The invention relates to an absorbent article having a topsheet and an absorbent core material. An acquisition distribution layer is located between the topsheet and the absorbent core material. The acquisition distribution layer is made of a three dimensional formed film with apertures, wherein the acquisition distribution layer has a body facing side, i.e. a female side, and a garment facing side, i.e. a male side. In accordance with the invention, the acquisition distribution layer defines a high void volume space. The large under-side void volume space provides space for unabsorbed fluid to flow over the top plane of saturated core regions and flow to new, unsaturated regions of the core material without contacting the topsheet, thereby avoiding a feeling of wetness for the user. Unabsorbed fluid results from repeated insults to a saturated zone of an absorbent core. In another embodiment, the acquisition distribution layer has at least one raised ridge extending upwards to a higher plane on the female side. The raised ridge runs in the machine direction for directing unabsorbed fluid to flow primarily in the machine direction of the absorptive device to help prevent side leakage. The xe2x80x9cmachine directionxe2x80x9d is a term of art that indicates the general direction of movement of materials during processing. Typically, if no separate tentering step is performed on the material, polymer strands within the material orient themselves generally in the machine direction of the film. In another embodiment a first and a second three dimensional apertured film forms an acquisition distribution layer having a further enlarged void volume space for flow of unabsorbed fluid and that provides a greater spacial separation between areas of containment of wetness and the topsheet. In still another embodiment, the acquisition distribution layer has a high loft, which forms relatively deep cells or buckets. When repeated insults are delivered to a saturated core region, a bucket or buckets in the insult region is filled. Subsequent insults result in fluid spilling over to adjacent buckets. The spill over action disperses the liquid volume of the insults over a larger area of the core material so that the fluid may be absorbed by unsaturated core material.
Further embodiments provide channels that are cut below a surface plane formed by the female or garment facing side of either the acquisition distribution layer having a large under-side void volume space, i.e., xe2x80x9cspill under embodimentxe2x80x9d or acquisition distribution layer having a high loft that forms buckets, i.e., xe2x80x9cspill over embodimentxe2x80x9d. The channels may also be used with other embodiments. The channels provide void space for fluid flow and directs the fluid flow in desired directions. The channels provide a new spill over passage that provides a spill over volume not previously possible with a xe2x80x9cspill underxe2x80x9d embodiment described above. Additionally, the channels improve the volume of the spill over in the xe2x80x9cspill overxe2x80x9d embodiment discussed above by providing a preferred directional pathway for spilling into the next xe2x80x9cbucketxe2x80x9d as well as by providing more volumetric pathways to spill and redistribute the fluid.